Mechanical properties and biocompatibility of low cost-type Ti-Mn system binary alloys for biomedical applications

Ti-29Nb-13Ta-4.6Zr (TNTZ) which was developed for biomedical applications, is a ß-type titanium alloy with a relatively low Young's modulus. However, its fabrication cost is high because the alloying elements of Nb and Ta, which are ß-stabilizers with high melting points, are expensive and rare metals. In this study, Ti-Mn system alloys were developed as low-cost titanium binary alloys for biomedical applications, and their mechanical properties (tensile strength and Young's modulus) and biocompatibility (bone contact ratio) were investigated to evaluate their possible use as next generation metallic biomaterials. Ti-12Mn has a tensile strength of approximately 950 MPa which is similar to those of annealed Ti-6A1-4V ELI (Extra Low interstitial) and insufficiently aged TNTZ. Ti-9.2Mn has the lowest Young's modulus of approximately 90 GPa among the alloys investigated. The mean values of bone contact ratios on Ti-12Mn were obtained 12 52 and 96 weeks after the implantation of rabbit femurs and were found to be slightly lower than the values for commercially pure Tialthough a small amount of Mn element was detected at a interfacial bone tissue with the concentration gradient at 96 weeks after implantation. However there appeared to be no significant effects of the release of Mn to the bone tissue on bone formation. From these results, it is considered that Ti-Mn system alloys are promising biomaterials with attractive mechanical proper-ties and relatively good biocompatibility.